The problem of changes in neurobehavioral functioning following low power density microwave fields has received considerable attention, especially in Eastern European countries. These investigators consistently report animals to be less reactive to electrical shock stimuli and more prone to fatigue than control animals. Work conducted in the United States is quite controversial. Little work has been done either in the United States or in Eastern European countries on the neurobehavioral effects of perinatal exposure. The purpose of this research is to study the effects of microwave exposure perinatally on neurobehavioral parameters and work performance in rats.